184 METABOLISM AND GROWTH FROM BIRTH TO PUBERTY. 



"In the period of development of boys, the years immediately preceding 

 puberty are of especial interest. By this time the figure has lost most of 

 its childish characteristics and the mind has reached a point of great in- 

 telligence. Although the individual has scarcely passed the half-way mark 

 in the years of growth, and has only attained half his future weight, yet he 

 resembles the adult much more than he resembles the infant. At this stage 

 the sex glands have not yet begun the rapid development of puberty with 

 its profound effect on the whole organism. Curiously enough there is a 

 sudden increase in the rate of growth which takes place at this time. In 

 fact, we may consider boys in the period of prepubescence as individuals of 

 adult form but of small size, growing rapidly, and as yet scarcely influenced 

 by the internal secretions of the sex glands. The study of their respiratory 

 exchanges may throw light on many problems." 



While we unfortunately have to differ with Du Bois as to these 

 experiments meeting the strict requirements for basal metabolism, 

 no paper has called more attention to the possibilities of changes in 

 metabolism in youth as compared to the adult period than has this. 

 We feel that the very high values found by Du Bois must have been 

 due in large part to muscular activity; consequently, a comparison is 

 of interest between his results and those of our observations with boys 

 between 12 and 13 years old, which were obtained under conditions 

 more closely approximating basal. 



On reference to figure 22 (page 133), we find records of 6 boys 

 between the ages of 12 and 13 years. Of these, 2 lie above the pro- 

 jected line indicating the general trend of the metabolism, and 4 

 below. From an examination of this line alone, one can see no increase 

 in the general trend of metabolism peculiar to this age; but since there 

 may be the reasonable objection that our boys were of abnormal 

 weight for their age, we may note the effect of computing the calories 

 per square meter. An examination of figure 45 shows us that of these 

 6 boys, 2 are again above the line representing the general trend and 

 4 below, with no indication of a supernormal metabolism. 



While the greater part of our observations were made with children 

 in the period of prepubescence, a few observations were made with boys 

 and girls after puberty was established. These are indicated on the 

 several charts by a special designation, i. e., by a square surrounding 

 the point. In figure 22 only one boy is so indicated, the point lying 

 somewhat above the general trend. In figure 45, in which the calories 

 per square meter of body-surface are referred to age, this point like- 

 wise lies above the line for the general trend. From this one observa- 

 tion, therefore, one might infer that there was a slight tendency for an 

 increase in metabolism after the onset of puberty rather than prior 

 to it; but obviously no special consideration should be given to a 

 single observation, especially as the determined value is not much 

 above the general trend. 



The influence of prepubescence upon the metabolism of girls is like- 

 wise of special physiological interest. We note in figure 23, which 



